The present invention relates to hydroxamate compounds which are inhibitors of histone deacetylase. The inventive compounds are useful as pharmaceuticals for the treatment of proliferative diseases.

Reversible acetylation of histones is a major regulator of gene expression that acts by altering accessibility of transcription factors to DNA. In normal cells, histone deacetylase (HDA) and histone acetyltrasferase together control the level of acetylation of histones to maintain a balance. Inhibition of HDA results in the accumulation of hyperacetylated histones, which results in a variety of cellular responses.

Inhibitors of HDA have been studied for their therapeutic effects on cancer cells. For example, butyric acid and its derivatives, including sodium phenylbutyrate, have been reported to induce apoptosis in vitro in human colon carcinoma, leukemia and retinoblastoma cell lines. However, butyric acid and its derivatives are not useful pharmacological agents because they tend to be metabolized rapidly and have a very short half-life in vivo. Other inhibitors of HDA that have been widely studied for their anti-cancer activities are trichostatin A and trapoxin. Trichostatin A is an antifungal and antibiotic and is a reversible inhibitor of mammalian HDA. Trapoxin is a cyclic tetrapeptide, which is an irreversible inhibitor of mammalian HDA. Although trichostatin and trapoxin have been studied for their anti-cancer activities, the in vivo instability of the compounds makes them less suitable as anti-cancer drugs.

Furthermore, WO-A-98/55449 discloses cinnamyl hydroxamic acids as inhibitors of histone deacetylase which are usefull in the treatment of proliferative diseases. WO-A-95/31977 reveals cinnamyl hydroxamic acid derivatives usefull in the treatment of cancer. WO-A-01/38322 discloses cinnamyl hydroxamic acids as inhibitors of histone deacetylase which may be usefull in the treatment of cancer.

The present invention provides efficacious deacetylase inhibitor compounds that are useful as pharmaceutical agents.

The compounds of the present invention are suitable as active agents in pharmaceutical compositions that are efficacious particularly for treating cellular proliferative ailments. The pharmaceutical composition has a pharmaceutical effective amount of the present active agent along with other pharmaceutically acceptable exipients, carriers, fillers, diluents and the like. The term pharmaceutically effective amount as used herein indicates an amount necessary to administer to a host to achieve a therapeutic result, especially an anti-tumor effect, e.g., inhibition of proliferation of malignant cancer cells, benign tumor cells or other proliferative cells.

The present invention provides hydroxamate compounds, e.g., hydroxamic acids, that are Inhibitors of deacetylases, preferably inhibitors of histone deacetylases. The hydroxamate compounds are highly suitable for treating tumors, including cancerous tumors. The hydroxamate compounds of the present invention have the following structure I wherein

• R₁ is H, halo, or a straight chain C₁-C₆ alkyl (especially methyl, ethyl or n-propyl, which methyl, ethyl and n-propyl substituents are unsubstituted or substituted by one or more substituents described below for alkyl substituents);
• R₂ is selected from H, C₁-C₁₀ alkyl, (preferably C₁-C₆ alkyl, e.g. methyl, ethyl or -CH₂CH₂-OH), C₄ - C₉ cycloalkyl, C₄ - C₉ heterocycloalkyl, C₄-C₉ heterocycloalkylalkyl, cycloalkylalkyl (e.g., cyclopropylmethyl), aryl, heteroaryl, arylalkyl (e.g. benzyl), heteroarylalkyl (e.g. pyridylmethyl), -(CH₂)_nC(O)R₆, -(CH₂)_nOC(O)R₆, amino acyl, HON-C(O)-CH=C(R₁)-aryl-alkyl- and -(CH₂)_nR₇;
• R₃ and R₄ are the same or different and independently H, C₁-C₆ alkyl, acyl or acylamino, or R₃ and R₄ together with the carbon to which they are bound represent C=S, or C=NR₈, or R₂ together with the nitrogen to which it is bound and R₃ together with the carbon to which it is bound can form a C₄ - C₉ heterocycloalkyl, a heteroaryl, a polyheteroaryl, a non-aromatic polyheterocycle, or a mixed aryl and non-aryl polyheterocycle ring;
• R₅ is selected from C₄-C₉ cycloalkyl, C₄-C₉ heterocycloalkyl, acyl, aryl, heteroaryl, arylalkyl (e.g. benzyl), heteroarylalkyl (e.g, pyridylmethyl), aromatic polycycles, non-aromatic polycycles, mixed aryl and non-aryl polycycles, polyheteroaryl, non-aromatic polyheterocycles, and mixed aryl and non-aryl polyheterocycles;
• n, n₁, n₂ and n₃ are the same or different and Independently selected from 0-6, when n₁ is 1-6, each carbon atom can be optionally and independently substituted with R₃ and/or R₄;
• X and Y are the same or different and Independently selected from H, halo, C₁-C₄ alkyl, such as CH₃ and CF₃, NO₂, C(O)R₁, OR₉, SR₉, CN, and NR₁₀R₁₁;
• R₆ is selected from H, C₁-C₆ alkyl, C₄-C₉ cycloalkyl, C₄-C₉ heterocycloalkyl, cycloalkylalkyl (e.g., cyclopropylmethyl), aryl, heteroaryl, arylalkyl (e.g., benzyl, 2-phenylethenyl), heteroarylalkyl (e.g., pyridylmethyl), OR₁₂, and NR₁₃R₁₄;
• R₇ is selected from OR₁₅, SR₁₅, S(O)R_16, SO₂R_17, NR₁₃R_14, and NR₁₂SO₂R₆;
• R₆ is selected from H, OR_15, NR₁₃R_14, C₁-C₆ alkyl, C₄-C₉ cycloalkyl, C₄- C₉ heterocycloalkyl, aryl, heteroaryl, arylalkyl (e.g., benzyl), and heteroarylalkyl (e.g., pyridylmethyl);
• R₉ is selected from C₁-C₄ alkyl, for example; CH₃ and CF₃, C(O)-alkyl, for example C(O)CH₃, and C(O)CF₃;
• R₁₀ and R₁₁ are the same or different and independently selected from H, C₁-C₄ alkyl, and -C(O)-alkyl;
• R₁₂ is selected from H, C₁-C₆ alkyl, C₄- C₈ cycloalkyl, C₄- C₉ heterocycloalkyl, C₄ - C₉ heterocycloalkylalkyl, aryl, mixed aryl and non-aryl polycycle, heteroaryl, arylalkyl (e.g., benzyl), and heteroarylalkyl (e.g., pyridylmethyl);
• R₁₃ and R₁₄ are the same or different and independently selected from H, C₁-C₆ alkyl, C₄- C₉ cycloalkyl, C₄-C₉ heterocycloalkyl, aryl, heteroaryl, arylalkyl (e.g., benzyl), heteroarylalkyl (e.g., pyridylmethyl), amino acyl, or R₁₃ and R₁₄ together with the nitrogen to which they are bound are C₄-C₉ heterocycloalkyl, heteroaryl, polyheteroaryl, non-aromatic polyheterocycle or mixed aryl and non-aryl polyhoterocycle;
• R₁₅ is selected from H, C₁-C₆ alkyl, C₄ - C₈ cycloalkyl, C₄- C₉ heterocycloalkyl, aryl, heteroaryl, arylalkyl, heteroarylalkyl and (CH₂)_mZR₁₂;
• R₁₆ is selected from C₁-C₆ alkyl, C₄-C₉ cycloalkyl, C₄-C₉ heterocycloalkyl, aryl, heteroaryl, polyheteroaryl, arylalkyl, heteroarylalkyl and (CH₂)_mZR₁₂;
• R₁₇ is selected from C₁-C₆ alkyl, C₄-C₉ cycloalkyl, C₄ - C₉ heterocycloalkyl, aryl, aromatic polycycles, heteroaryl, arylalkyl, heteroarylalkyl, polyheteroaryl and NR₁₃R₁₄;
• m is an integer selected from 0 to 6; and
• Z is selected from O, NR₁₃, S and S(O),

• "alkyl" is straight or branched C₁-C₆alkyl which is unsubstituted or substituted by one or more substituents, including unsaturation (i.e. there are one or more double or triple C-C bonds), acyl, cycloalkyl, halo, oxyalkyl, alkylamino, aminoalkyl, acylamino and OR₁₅;
• "cycloalkyl" is a C₃-C₉ cycloalkyl group which is unsubstituted or substituted by one or more substituents selected from C₁-C₆ alkyl, halo, hydroxy, aminoalkyl, oxyalkyl, alkylamino, and OR₁₅;
• "cycloalkylalkyl" is a radical of the formula -(CH₂)_n5-cycloalkyl wherein n5 is a number from 1-6 and is unsubstituted or substituted in the alkyl portion or in the cycloalkyl portion by a substituent listed above for alkyl and cycloalkyl;
• "heterocycloalkyl" is a 3 to 9 membered aliphatic ring which contains from one to three heteroatoms selected from nitrogen, sulfur and oxygen and is unsubstituted or substituted on the carbon atoms by one or more substituents C₁-C₆ alkyl, C₄ - C₉ cycloalkyl, aryl, heteroaryl, arylalkyl, heteroarylalkyl, halo, amino, alkyl amino and OR₁₅, wherein nitrogen heteroatoms are unsubstituted or substituted by C₁-C₄ alkyl, arylalkyl, and heteroarylalkyl, acyl, aminoacyl, alkylsulfonyl, and arylsulfonyl;
• "aryl" is phenyl and phenyl substituted by one or more substituents C₁-C₆ alkyl, cycloalkylalkyl, O(CO)alkyl, oxyalkyl, halo, nitro, amino, alkylamino, aminoalkyl, alkyl ketones, nitrile, carboxyalkyl, alkylsulfonyl, aminosulfonyl, arylsulfonyl, and OR₁₅:
  • "arylalkyl" is a group of the formula -(CH₂)_n5-aryl, -(CH₂)_n5-1-(CHaryl)-(CH₂)_n5-aryl or -(CH₂)_n5-1CH(aryl)(aryl), wherein n5 is a number from 1-6 and wherein arylalkyl is unsubstituted or substituted in the alkyl moiety or the aryl moiety or both as described above for alkyl and aryl;
  • "heteroaryl" is a 5 to 7 member aromatic ring containing from 1 to 4 heteroatoms selected from N, O and S and is unsubstituted or substituted on a carbon atom by one or more substituents selected from alkyl and another heteroaryl substituent, wherein nitrogen atoms are unsubstituted or substituted by R₁₃, especially by C₁ - C₄ alkyl, acyl, aminoacyl, and sulfonyl;
  • "heteroarylalkyl" is a group of the formula -(CH₂)_n5-heteroaryl wherein heteroaryl and n5 are as defined above and the bridging group is linked to a carbon or a nitrogen of the heteroaryl portion;
  • "aromatic polycycle" is naphthyl or naphthyl substituted by one or more substituents selected from C₁-C₆ alkyl, cycloalkylalkyl, oxyalkyl, halo, nitro, amino, alkylamino, aminoalkyl, alkyl ketones, nitrile, carboxyalkyl, alkylsulfonyl, arylsulfonyl, aminosulfonyl and OR₁₅;
  • "non-aromatic polycycle" is a bicyclic or tricyclic fused ring system where each ring can be 4-9 membered and each ring contains zero, 1 or more double and/or triple bonds, wherein a non-aromatic polycycle is unsubstituted or substituted as described above for cycloalkyl;
  • "amino acyl" is a group of the formula -C(O)-(CH₂)_n-C(H)(NR₁₃R₁₄)-(CH₂)_n-R₅;
  • "mixed aryl and non-aryl polycycles" are bicyclic or tricyclic fused ring systems where each ring can be 4 - 9 membered and at least one ring is aromatic, wherein mixed aryl and non-aryl polycycles are unsubstituted or substituted by nitro or as described above for cycloalkyl;
  • "polyheteroaryl" is a bicyclic or tricyclic fused ring system where each ring can independently be 5 or 6 membered and contain 1-4 heteroatoms chosen from O, N or S such that the fused ring system is aromatic, wherein polyheteroaryl is unsubstituted or substituted on a carbon atom by one or more substituents selected from alkyl and a substituent of the formula -O-(CH₂CH=CH(CH₃)(CH₂))_1-3H and wherein nitrogen atoms are unsubstituted or substituted by R₁₃, especially by C₁- C₄ alkyl, acyl, aminoacyl, and sulfonyl;
  • ''non-aromatic polyheterocycle" is a bicyclic or tricyclic fused ring system where each ring can be 4 - 9 membered, contain 1-4 heteroatoms chosen from O, N or S and contain zero or one or more C-C double or triple bonds, wherein a non-aromatic polyheterocycle is unsubstituted or substituted on a carbon atom by one or more substituents alkyl and wherein nitrogen atoms are unsubstituted or substituted by R₁₃, especially by C₁ - C₄ alkyl, acyl, aminoacyl, and sulfonyl;
  • "mixed aryl and non-aryl polyheterocycles" are bicyclic or tricyclic fused ring systems where each ring can be 4 - 9 membered, contain one or more heteroatoms chosen from O, N or S, and at least one of the rings must be aromatic, wherein mixed aryl and non-aryl polyheterocycles are unsubstituted or substituted on a carbon atom by one or more substituents selected from -N-OH, =N-OH and alkyl and wherein nitrogen atoms are unsubstituted or substituted by R₁₃, especially by C₁ - C₄ alkyl, acyl, aminoacyl, and sulfonyl;
  • "acyl" is a group of the formula -C(O)-W, -OC(O)-W, -C(O)-O-W and -C(O)NR₁₃R₁₄, where W is R₁₆, H or cycloalkylalkyl;
  • "acylamino" is a group of the formula -N(R₁₂)C(O)-W, -N(R₁₂)C(O)-O-W, and -N(R₁₂)C(O)-NHOH, wherein R₁₂ and W are as defined above;
  and wherein
  • "HON-C(O)-CH=C(R₁)-aryl-alkyl-" is a group of the formula
  wherein n₄ is 0-3 and X and Y are as defined above;

As appropriate, unsubstituted means that there is no substituent or that the only substituents are hydrogen.

Halo substituents are selected from fluoro, chloro, bromo and iodo, preferably fluoro or chloro.

Alkyl substituents include straight and branched C₁-C₆alkyl, unless otherwise noted. Examples of suitable straight and branched C₁-C₆alkyl substituents include methyl; ethyl, n-propyl, 2-propyl, n-butyl, sec-butyl, t-butyl, and the like. Unless otherwise noted, the alkyl substituents include both unsubstituted alkyl groups and alkyl groups that are substituted by one or more suitable substituents, including unsaturation (i.e. there are one or more double or triple C-C bonds), acyl, cycloalkyl, halo, oxyalkyl, alkylamino, aminoalkyl, acylamino and OR₁₅, for example, alkoxy. Preferred substituents for alkyl groups include halo, hydroxy, alkoxy, oxyalkyl, alkylamino, and aminoalkyl.

Cycloalkyl substituents include C₃-C₉ cycloalkyl groups, such as cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl and the like, unless otherwise specified. Unless otherwise noted, cycloalkyl substituents include both unsubstituted cycloalkyl groups and cycloalkyl groups that are substituted by one or more suitable substituents, including C₁-C₈ alkyl, halo, hydroxy, aminoalkyl, oxyalkyl, alkylamino, and OR₁₅, such as alkoxy. Preferred substituents for cycloalkyl groups include halo, hydroxy, alkoxy, oxyalkyl, alkylamino and aminoalkyl.

The above discussion of alkyl and cycloalkyl substituents also applies to the alkyl portions of other substituents, such as without limitation, alkoxy, alkyl amines, alkyl ketones, arylalkyl, heteroarylalkyl, alkylsulfonyl and alkyl ester substituents and the like.

Heterocycloalkyl substituents include 3 to 9 membered aliphatic rings, such as 4 to 7 membered aliphatic rings, containing from one to three heteroatoms selected from nitrogen, sulfur and oxygen. Examples of suitable heterocycloalkyl substituents include pyrrolidyl, tetrahydrofuryl, tetrahydrothiofuranyl, piperidyl, piperazyl, tetrahydropyranyl, morphilino, 1,3-diazapane, 1,4-diazapane, 1,4-oxazepane, and 1,4-oxathiapane, Unless otherwise noted, the rings are unsubstituted or substuted on the carbon atoms by one or more suitable substituents, including C₁-C₆ alkyl, C₄ - C₉ cycloalkyl, aryl, heteroaryl, arylalkyl (e.g., benzyl), and heteroarylalkyl (e.g., pyridylmethyl), halo, amino, alkyl amino and OR₁₅, for example alkoxy. Unless otherwise noted, nitrogen heteroatoms are unsubstituted or substituted by H, C₁-C₄ alkyl, arylalkyl (e.g., benzyl), and heteroarylalkyl (e.g., pyridylmethyl), acyl, aminoacyl, alkylsulfonyl, and arylsulfonyl.

Cycloalkylalkyl substituents include compounds of the formula -(CH₂)_n5-cycloalkyl wherein n5 is a number from 1-6. Suitable cycloalkylalkyl substituents include cyclopentylmethyl-, cyclopentylethyl, cyclohexylmethyl and the like. Such substituents are unsubstituted or substituted in the alkyl portion or in the cycloalkyl portion by a suitable substituent, including those listed above for alkyl and cycloalkyl.

Aryl substituents include unsubstituted phenyl and phenyl substituted by one or more suitable substituents, including C₁-C₆ alkyl, cycloalkylalkyl (e.g., cyclopropylmethyl), O(CO)alkyl, oxyalkyl, halo, nitro, amino, alkylamino, aminoalkyl, alkyl ketones, nitrile, carboxyalkyl, alkylsulfonyl, aminosulfonyl, arylsulfonyl, and OR₁₅, such as alkoxy. Preferred substituents include including C₁-C₆ alkyl, cycloalkyl (e.g., cyclopropylmethyl), alkoxy, oxyalkyl, halo, nitro, amino, alkylamino, aminoalkyl, alkyl ketones, nitrile, carboxyalkyl, alkylsulfonyl, arylsulfonyl, and aminosulfonyl. Examples of suitable aryl groups include C₁-C₄alkylphenyl, C₁-C₄alkoxyphenyl, trifluoromethylphenyl, methoxyphenyl, hydroxyethylphenyl, dimethylaminophenyl, aminopropylphenyl, carbethoxyphenyl, methanesulfonylphenyl and tolylsulfonylphenyl.

Aromatic polycycles include naphthyl, and naphthyl substituted by one or more suitable substituents, including C₁-C₆ alkyl, cycloalkylalkyl (e.g., cyclopropylmethyl), oxyalkyl, halo, nitro, amino, alkylamino, aminoalkyl, alkyl ketones, nitrile, carboxyalkyl, alkylsulfonyl, arylsulfonyl, aminosulfonyl and OR₁₅, such as alkoxy.

Heteroaryl substituents include compounds with a 5 to 7 member aromatic ring containing one or more heteroatoms, for example from 1 to 4 heteroatoms, selected from N, O and S. Typical heteroaryl substituents include furyl, thienyl, pyrrole, pyrazole, triazole, thiazole, oxazole, pyridine, pyrimidine, isoxazolyl, pyrazine and the like. Unless otherwise noted, heteroaryl substituents are unsubstituted or substituted on a carbon atom by one or more suitable substituents, including alkyl, the alkyl substituents identified above, and another heteroaryl substituent. Nitrogen atoms are unsubstituted or substituted, for example by R₁₃; especially useful N substituents include H, C₁- C₄ alkyl, acyl, aminoacyl, and sulfonyl.

Arylalkyl substituents include groups of the formula -(CH₂)_n5-aryl, -(CH₂)_n5-1-(CHaryl)-(CH₂)_n5-aryl or -(CH₂)_n5-1CH(aryl)(aryl) wherein aryl and n5 are as defined above. Such arylalkyl substituents include benzyl, 2-phenylethyl, 1-phenylethyl, tolyl-3-propyl, 2-phenylpropyl, diphenylmethyl, 2-diphenylethyl, 5,5-dimethyl-3-phenylpentyl and the like. Arylalkyl substituents are unsubstituted or substituted in the alkyl moiety or the aryl moiety or both as described above for alkyl and aryl substituents.

Heteroarylalkyl substituents include groups of the formula -(CH₂)_n5-heteroaryl wherein heteroaryl and n5 are as defined above and the bridging group is linked to a carbon or a nitrogen of the heteroaryl portion, such as 2-, 3- or 4-pyridylmethyl, imidazolylmethyl, quinolylethyl, and pyrrolylbutyl. Heteroaryl substituents are unsubstituted or substituted as discussed above for heteroaryl and alkyl substituents.

Amino acyl substituents include groups of the formula -C(O)-(CH₂)_n-C(H)(NR₁₃R₁₄)-(CH₂)_n-R₅ wherein n, R₁₃, R₁₄ and R₅ are described above. Suitable aminoacyl substituents include natural and non-natural amino acids such as glycinyl, D-tryptophanyl, L-lysinyl, D- or L-homoserinyl, 4-aminobutryic acyl, ±-3-amin-4-hexenoyl.

Non-aromatic polycycle substituents include bicyclic and tricyclic fused ring systems where each ring can be 4-9 membered and each ring can contain zero, 1 or more double and/or triple bonds. Suitable examples of non-aromatic polycycles include decalin, octahydroindene, perhydrobenzocycloheptene, perhydrobenzo-[f]-azulene. Such substituents are unsubstituted or substituted as described above for cycloalkyl groups.

Mixed aryl and non-aryl polycycle substituents include bicyclic and tricyclic fused ring systems where each ring can be 4 - 9 membered and at least one ring is aromatic. Suitable examples of mixed aryl and non-aryl polycycles include methylenedioxyphenyl, bis-methylenedioxyphenyl, 1,2,3,4-tetrahydronaphthalene, dibenzosuberane, dihdydroanthracene, 9H-fluorene. Such substituents are unsubstituted or substituted by nitro or as described above for cycloalkyl groups.

Polyheteroaryl substituents include bicyclic and tricyclic fused ring systems where each ring can independently be 5 or 6 membered and contain one or more heteroatom, for example, 1, 2, 3, or 4 heteroatoms, chosen from O, N or S such that the fused ring system is aromatic. Suitable examples of polyheteroaryl ring systems include quinoline, isoquinoline, pyridopyrazine, pyrrolopyridine, furopyridine, indole, benzofuran, benzothiofuran, benzindole, benzoxazole, pyrroloquinoline, and the like. Unless otherwise noted, polyheteroaryl substituents are unsubstituted or substituted on a carbon atom by one or more suitable substituents, including alkyl, the alkyl substituents identified above and a substituent of the formula -O-(CH₂CH=CH(CH₃)(CH₂))_1-3H. Nitrogen atoms are unsubstituted or substituted, for example by R₁₃; especially useful N substituents include H, C₁-C₄ alkyl, acyl, aminoacyl, and sulfonyl.

Non-aromatic polyheterocyclic substituents include bicyclic and tricyclic fused ring systems where each ring can be 4 - 9 membered, contain one or more heteroatom, for example, 1, 2, 3, or 4 heteroatoms, chosen from O, N or S and contain zero or one or more C-C double or triple bonds. Suitable examples of non-aromatic polyheterocycles include hexitol, cis-perhydro-cyclohepta[b]pyridinyl, decahydro-benzo[f][1,4]oxazepinyl, 2,8-dioxabicyclo[3.3.0]octane, hexahydro-thieno[3,2-b]thiophene, perhydropyrrolo[3,2-b]pyrrole, perhydronaphthyridine, perhydro-1H-dicyclopenta[b,e]pyran. Unless otherwise noted, non-aromatic polyheterocyclic substituents are unsubstituted or substituted on a carbon atom by one or more substituents, including alkyl and the alkyl substituents identified above. Nitrogen atoms are unsubstituted or substituted, for example, by R₁₃; especially useful N substituents include H, C₁ - C₄ alkyl, acyl, aminoacyl, and sulfonyl.

Mixed aryl and non-aryl polyheterocycles substituents include bicyclic and tricyclic fused ring systems where each ring can be 4 - 9 membered, contain one or more heteroatom chosen from O, N or S, and at least one of the rings must be aromatic. Suitable examples of mixed aryl and non-aryl polyheterocycles include 2,3-dihydroindole, 1,2,3,4-tetrahydroquinoline, 5,11-dihydro-10H-dibenz[b,e][1,4]diazepine, 5H-dibenzo[b,e][1,4]diazepine, 1,2-dihydropyrrolo[3,4-b][1,5]benzodiazepine, 1,5-dihydropyrido[2,3-b][1,4]diazepin-4-one, 1,2,3,4,6,11-hexahydro-benzo[b]pyrido[2,3-e][1,4]diazepin-5-one. Unless otherwise noted, mixed aryl and non-aryl polyheterocyclic substituents are unsubstituted or substituted on a carbon atom by one or more suitable substituents, including, -N-OH, =N-OH, alkyl and the alkyl substituents identified above. Nitrogen atoms are unsubstituted or substituted, for example, by R₁₃; especially useful N substituents include H, C₁ - C₄ alkyl, acyl, aminoacyl, and sulfonyl.

Amino substituents include primary, secondary and tertiary amines and in salt form, quaternary amines. Examples of amino substituents include mono- and di-alkylamino, mono- and di-aryl amino, mono- and di-arylalkyl amino, aryl-arylalkylamino, alkyl-arylamino, alkyl-arylalkylamino and the like.

Sulfonyl substituents include alkylsulfonyl and arylsulfonyl, for example methane sulfonyl, benzene sulfonyl, tosyl and the like.

Acyl substituents include groups of the formula -C(O)-W, -OC(O)-W, -C(O)-O-W and -C(O)NR₁₃R₁₄, where W is R₁₆, H or cycloalkylalkyl.

Acylamino substituents include groups of the formula -N(R₁₂)C(O)-W, -N(R₁₂)C(O)-O-W, and -N(R₁₂)C(O)-NHOH and R₁₂ and W are as defined above.

The R₂ substituent HON-C(O)-CH=C(R₁)-aryl-alkyl- is a group of the formula wherein n₄ is 0-3 and X and Y are as defined above.

Preferences for each of the substituents include the following:

• R₁ is H, halo, or a straight chain C₁-C₄ alkyl;
• R₂ is selected from H, C₁-C₆ alkyl, C₄ - C₉ cycloalkyl, C₄ - C₉ heterocycloalkyl, cycloalkylalkyl, aryl, heteroaryl, arylalkyl, heteroarylalkyl, -(CH₂)_nC(O)R₆, amino acyl, and -(CH₂)_nR₇;
• R₃ and R₄ are the same or different and independently selected from H, and C₁-C₆ alkyl, or R₃ and R₄ together with the carbon to which they are bound represent C=O, C=S, or C=NR₈;
• R₅ is selected from H, C₁-C₆ alkyl, C₄ - C₉ cycloalkyl, C₄ - C₉ heterocycloalkyl, aryl, heteroaryl, arylalkyl, heteroarylalkyl, an aromatic polycycle, a non-aromatic polycycle, a mixed aryl and non-aryl polycycle, polyheteroaryl, a non-aromatic polyheterocycle, and a mixed aryl and non-aryl polyheterocycle;
• n, n₁, n₂ and n₃ are the same or different and independently selected from 0-6, when n₁ is 1-6, each carbon atom is unsubstituted or independently substituted with R₃ and/or R₄;
• X and Y are the same or different and independently selected from H, halo, C₁-C₄ alkyl, CF₃, NO₂, C(O)R₁, OR₉, SR₉, CN, and NR₁₀R₁₁;
• R₆ is selected from H, C₁-C₆ alkyl, C₄-C₉ cycloalkyl, C₄-C₉ heterocycloalkyl, cycloalkylalkyl, aryl, heteroaryl, arylalkyl, heteroarylalkyl, OR₁₂, and NR₁₃R₁₄;
• R₇ is selected from OR₁₅, SR₁₅, S(O)R₁₆, SO₂R₁₇, NR₁₃R₁₄, and NR₁₂SO₂R₆;
• R₈ is selected from H, OR₁₅, NR₁₃R₁₄, C₁-C₆ alkyl, C₄-C₉ cycloalkyl, C₄-C₉ heterocycloalkyl, aryl, heteroaryl, arylalkyl, and heteroarylalkyl;
• R₉ is selected from C₁ - C₄ alkyl and C(O)-alkyl;
• R₁₀ and R₁₁ are the same or different and independently selected from H, C₁-C₄ alkyl, and -C(O)-alkyl;
• R₁₂ is selected from H, C₁-C₆ alkyl, C₄ - C₉ cycloalkyl, C₄ - C₉ heterocycloalkyl, aryl, heteroaryl, arylalkyl, and heteroarylalkyl;
• R₁₃ and R₁₄ are the same or different and independently selected from H, C₁-C₆ alkyl, C₄ - C₉ cycloalkyl, C₄ - C₉ heterocycloalkyl, aryl, heteroaryl, arylalkyl, heteroarylalkyl and amino acyl;
• R₁₅ is selected from H, C₁-C₆ alkyl, C₄ - C₉ cycloalkyl, C₄ - C₉ heterocycloalkyl, aryl, heteroaryl, arylalkyl, heteroarylalkyl and (CH₂)_mZR₁₂;
• R₁₆ is selected from C₁-C₆ alkyl, C₄ - C₉ cycloalkyl, C₄ - C₉ heterocycloalkyl, aryl, heteroaryl, arylalkyl, heteroarylalkyl and (CH₂)_mZR₁₂;
• R₁₇ is selected from C₁-C₆ alkyl, C₄ - C₉ cycloalkyl, C₄ - C₉ heterocycloalkyl, aryl, heteroaryl, arylalkyl, heteroarylalkyl and NR₁₃R₁₄;
• m is an integer selected from 0 to 6; and
• Z is selected from O, NR₁₃, S, S(O).

Useful compounds of the formula I include those wherein each of R₁, X, Y, R₃, and R₄ is H, including those wherein one of n₂ and n₃ is zero and the other is 1, especially those wherein R₂ is H or -CH₂-CH₂-OH.

One suitable genus of hydroxamate compounds are those of formula la wherein

• n₄ is 0-3,
• R₂ is selected from H, C₁-C₆ alkyl, C₄ - C₉ cycloalkyl, C₄ - C₉ heterocycloalkyl, cycloalkylalkyl, aryl, heteroaryl, arylalkyl, heteroarylalkyl, -(CH₂)_nC(O)R₆, amino acyl and -(CH₂)_nR₇;
• R₅' is heteroaryl, heteroarylalkyl (e.g., pyridylmethyl), aromatic polycycles, non-aromatic polyoycles, mixed aryl and non-aryl polycycles, polyheteroaryl, or mixed aryl and non-aryl polyheterocycles,

Another suitable genus of hydroxamate compounds are those of formula la wherein

• n₄ is 0-3,
• R₂ is selected from H, C₁-C₆ alkyl, C₄ - C₉ cycloalkyl, C₄ - C₉ heterocycloalkyl, cycloalkylalkyl, aryl, heteroaryl, arylalkyl, heteroarylalkyl, -(CH₂)_nC(O)R₆, amino acyl and -(CH₂)_nR₇;
• R₅' is aryl, arylalkyl, aromatic polycycles, non-aromatic polycycles, and mixed aryl and non-aryl polycycles; especially aryl, such as p-fluorophenyl, p-chlorophenyl, p-O-C₁-C₄-alkylphenyl, such as p-methoxyphenyl, and p-C₁-C₄-alkylphenyl; and arylalkyl, such as benzyl, ortho, meta orpara-fluorobenzyl, ortho, meta or para-chlorobenzyl, ortho, meta orpara-mono, di or tri-O-C₁-C₄-alkylbenzyl, such as ortho, meta or para-methoxybenzyl, m,p-diethoxybenzyl, o,m,p-triimethoxybenzyl , and ortho, meta or para- mono, di or tri C₁-C₄-alkylphenyl, such as p-methyl, m,m-diethylphenyl,

Another interesting genus are the compounds of formula lb wherein

• R₂' is selected from H, C₁-C₆ alkyl, C₄-C₆ cycloalkyl, cycloalkylalkyl (e.g., cyclopropylmethyl), -(CH₂)_2-4OR₂₁ where R₂₁ is H, methyl, ethyl, propyl, and i-propyl, and
• R₅" is unsubstituted 1H-indol-3-yl, benzofuran-3-yl or quinolin-3-yl, or substituted 1H-indol-3-yl, such as 5-fluoro-1H-indol-3-yl or 5-methoxy-1H-indol-3-yl, benzofuran-3-yl or quinolin-3-yl,

Another interesting genus of hydroxamate compounds are the compounds of formula lc wherein

• the ring containing Z₁ is aromatic or non-aromatic, which non-aromatic rings are saturated or unsaturated,
• Z₁ is O, S or N-R₂₀,
• R₁₈ is H, halo, C₁-C₆alkyl (methyl, ethyl, t-butyl), C₃-C₇cycloalkyl, aryl, for example unsubstituted phenyl or phenyl substituted by 4-OCH₃ or 4-CF₃, or heteroaryl, such as 2-furanyl, 2-thiophenyl or 2-, 3- or 4-pyridyl;
• R₂₀ is H, C₁-C₆alkyl, C₁-C₆alkyl-C₃-C₉cycloalkyl (e.g., cyclopropylmethyl), aryl, heteroaryl, arylalkyl (e.g., benzyl), heteroarylalkyl (e.g., pyridylmethyl), acyl (acetyl, propionyl, benzoyl) or sulfonyl (methanesulfonyl, ethanesulfonyl, benzenesulfonyl, toluenesulfonyl);
• A₁ is 1, 2 or 3 substituents which are independently H, C₁-C-₆alkyl, -OR₁₉, halo, alkylamino, aminoalkyl, halo, or heteroarylalkyl (e.g., pyridylmethyl),
• R₁₉ is selected from H, C₁-C₆alkyl, C₄-C₉cycloalkyl, C₄-C₉heterocycloalkyl, aryl, heteroaryl, arylalkyl (e.g., benzyl), heteroarylalkyl (e.g., pyridylmethyl) and -(CH₂CH=CH(CH₃)(CH₂))_1-3H;
• R₂ is selected from H, C₁-C₆ alkyl, C₄ - C₉ cycloalkyl, C₄ - C₉ heterocycloalkyl, cycloalkylalkyl, aryl, heteroaryl, arylalkyl, heteroarylalkyl, -(CH₂)_nC(O)R₆, amino acyl and -(CH₂)_nR₇;
• v is 0, 1 or 2,
• p is 0-3, and
• q is 1-5 and r is 0 or
• q is 0 and r is 1-5,

Especially useful compounds of formula Ic are those wherein R₂ is H, or -(CH₂)_pCH₂OH, wherein p is 1-3, especially those wherein R₁ is H; such as those wherein R₁ is H and X and Y are each H, and wherein q is 1-3 and r is 0 or wherein q is 0 and r is 1-3, especially those wherein Z₁ is N-R₂₀. Among these compounds R₂ is preferably H or -CH₂-CH₂-OH and the sum of q and r is preferably 1.

Another interesting genus of hydroxamate compounds are the compounds of formula Id wherein

• Z₁ is O, S or N-R₂₀,
• R₁₈ is H, halo, C₁-C₆alkyl (methyl, ethyl, t-butyl), C₃-C₇cycloalkyl, aryl, for example, unsubstituted phenyl or phenyl substituted by 4-OCH₃ or 4-CF₃, or heteroaryl,
• R₂₀ is H, C₁-C₆alkyl, C₁-C₆alkyl-C₃-C₉cycloalkyl (e.g., cyclopropylmethyl), aryl, heteroaryl, arylalkyl (e.g., benzyl), heteroarylalkyl (e.g., pyridylmethyl), acyl (acetyl, propionyl, benzoyl) or sulfonyl (methanesulfonyl, ethanesulfonyl, benzenesulfonyl, toluenesulfonyl);
• A₁ is 1, 2 or 3 substituents which are independently H, C₁-C-₆alkyl, -OR₁₉, or halo,
• R₁₉ is selected from H, C₁-C₆alkyl, C₄-C₉cycloalkyl, C₄-C₉heterocycloalkyl, aryl, heteroaryl, arylalkyl (e.g., benzyl), and heteroarylalkyl (e.g., pyridylmethyl);
• p is 0-3, and
• q is 1-5 and r is 0 or
• q is 0 and r is 1-5,

Especially useful compounds of formula ld are those wherein R₂ is H, or -(CH₂)_pCH₂OH, wherein p is 1-3, especially those wherein R₁ is H; such as those wherein R₁ is H and X and Y are each H, and wherein q is 1-3 and r is 0 or wherein q is 0 and r is 1-3. Among these compounds R₂ is preferably H or -CH₂-CH₂-OH and the sum of q and r is preferably 1.

The present invention further relates to compounds of the formula le or a pharmaceutical acceptable salt thereof. The variable substituents are as defined above.

Especially useful compounds of formula le are those wherein R₁₈ is H, fluoro, chloro, bromo, a C₁-C₄alkyl group, a substituted C₁-C₄alkyl group, a C₃-C₇cycloalkyl group, unsubstituted phenyl, phenyl substituted in the para position, or a heteroaryl (e.g., pyridyl) ring.

Another group of useful compounds of formula le are those wherein R₂ is H, or - (CH₂)_pCH₂OH, wherein p is 1-3, especially those wherein R₁ is H; such as those wherein R₁ is H and X and Y are each H, and wherein q is 1-3 and r is 0 or wherein q is 0 and r is 1-3. Among these compounds R₂ is preferably H or -CH₂-CH₂-OH and the sum of q and r is preferably 1.

Another group of useful compounds of formula le are those wherein R₁₈ is H, methyl, ethyl, t-butyl, trifluoromethyl, cyclohexyl, phenyl, 4-methoxyphenyl, 4-trifluoromethylphenyl, 2-furanyl, 2-thiophenyl, or 2-, 3- or 4-pyridyl wherein the 2-furanyl, 2-thiophenyl and 2-, 3- or 4-pyridyl substituents are unsubstituted or substituted as described above for heteroaryl rings; R₂ is H, or -(CH₂)_pCH₂OH, wherein p is 1-3; especially those wherein R₁ is H and X and Y are each H, and wherein q is 1-3 and r is 0 or wherein q is 0 and r is 1-3. Among these compounds R₂ is preferably H or -CH₂-CH₂-OH and the sum of q and r is preferably 1.

Those compounds of formula le wherein R₂₀ is H or C₁-C₆alkyl, especially H, are important members of each of the subgenuses of compounds of formula le described above.

N-hydroxy-3-[4-[[(2-hydroxyethyl)[2-(1 1H-indol-3-yl)ethyl]-amino]methyl]phenyl]-2E-2-propenamide, N-hydroxy-3-[4-[[[2-(1 H-indol-3-yl)ethyl]-amino]methyl]phenyl]-2E-2-propenamide and N-hydroxy-3-[4-[[[2-(2-methyl-1H-indol-3-yl)-ethyl]-amino]methyl]phenyl]-2E-2-propenamide, or a pharmaceutically acceptable salt thereof, are important compounds of formula le.

The present invention further relates to the compounds of the formula If or a pharmaceutically acceptable salt thereof. The variable substituents are as defined above.

Useful compounds of formula If are those wherein R₂ is H, or -(CH₂)_pCH₂OH, wherein p is 1-3, especially those wherein R₁ is H; such as those wherein R₁ is H and X and Y are each H, and wherein q is 1-3 and r is 0 or wherein q is 0 and r is 1-3. Among these compounds R₂ is preferably H or -CH₂-CH₂-OH and the sum of q and r is preferably 1.

N-hydroxy-3-[4-[[[2-(benzofur-3-yl)-ethyl]-amino]methyl]phenyl]-2E-2-propenamide, or a pharmaceutically acceptable salt thereof, is an important compound of formula If.

The compounds described above are often used in the form of a pharmaceutically acceptable salt. Pharmaceutically acceptable salts include, when appropriate, pharmaceutically acceptable base addition salts and acid addition salts, for example, metal salts, such as alkali and alkaline earth metal salts, ammonium salts, organic amine addition salts, and amino acid addition salts, and sulfonate salts. Acid addition salts include inorganic acid addition salts such as hydrochloride, sulfate and phosphate, and organic acid addition salts such as alkyl sulfonate, arylsulfonate, acetate, maleate, fumarate, tartrate, citrate and lactate. Examples of metal salts are alkali metal salts, such as lithium salt, sodium salt and potassium salt, alkaline earth metal salts such as magnesium salt and calcium salt, aluminum salt, and zinc salt. Examples of ammonium salts are ammonium salt and tetramethylammonium salt. Examples of organic amine addition salts are salts with morpholine and piperidine. Examples of amino acid addition salts are salts with glycine, phenylalanine, glutamic acid and lysine. Sulfonate salts include mesylate, tosylate and benzene sulfonic acid salts.

As is evident to those skilled in the art, the many of the deacetylase inhibitor compounds of the present invention contain asymmetric carbon atoms. It should be understood, therefore, that the individual stereoisomers are contemplated as being included within the scope of this invention.

The hydroxamate compounds of the present invention can be produced by known organic synthesis methods. For example, the hydroxamate compounds can be produced by reacting methyl 4-formyl cinnamate with tryptamine and then converting the reactant to the hydroxamate compounds. As an example, methyl 4-formyl cinnamate 2, is prepared by acid catalyzed esterification of 4-formylcinnamic acid 3 (Bull. Chem. Soc. Jpn. 1995; 68:2355-2362). An alternate preparation of methyl 4-formyl cinnamate 2 is by a Pd-catalyzed coupling of methyl acrylate 4 with 4-bromobenzaldehyde 5.

Additional starting materials can be prepared from 4-carboxybenzaldehyde 6, and an exemplary method is illustrated for the preparation of aldehyde 9, shown below. The carboxylic acid in 4-carboxybenzaldehyde 6 can be protected as a silyl ester (e.g., the t-butyldimethylsilyl ester) by treatment with a silyl chloride (e.g., t-butyldimethylsilyl chloride) and a base (e.g. triethylamine) in an appropriate solvent (e.g., dichloromethane). The resulting silyl ester 7 can undergo an olefination reaction (e.g., a Homer-Emmons olefination) with a phosphonate ester (e.g., triethyl 2-phosphonopropionate) in the presence of a base (e.g., sodium hydride) in an appropriate solvent (e.g., tetrahydrofuran (THF)). Treatment of the resulting diester with acid (e.g., aqueous hydrochloric acid) results in the hydrolysis of the silyl ester providing acid 8. Selective reduction of the carboxylic acid of 8 using, for example, borane-dimethylsuflide complex in a solvent (e.g., THF) provides an intermediate alcohol. This intermediate alcohol could be oxidized to aldehyde 9 by a number of known methods, including, but not limited to, Swem oxidation, Dess-Martin periodinane oxidation, Moffatt oxidation and the like.

The aldehyde starting materials 2 or 9 can be reductively aminated to provide secondary or tertiary amines. This is illustrated by the reaction of methyl 4-formyl cinnamate 2 with tryptamine 10 using sodium triacetoxyborohydride (NaBH(OAc)₃) as the reducing agent in dichloroethane (DCE) as solvent to provide amine 11. Other reducing agents can be used, e.g., sodium borohydride (NaBH₄) and sodium cyanoborohydride (NaBH₃CN), in other solvents or solvent mixtures in the presence or absence of acid catalysts (e.g., acetic acid and trifluoroacetic acid). Amine 11 can be converted directly to hydroxamic acid 12 by treatment with 50% aqueous hydroxylamine in a suitable solvent (e.g., THF in the presence of a base, e.g., NaOH). Other methods of hydroxamate formation are known and include reaction of an ester with hydroxylamine hydrochloride and a base (e.g., sodium hydroxide or sodium methoxide) in a suitable solvent or solvent mixture (e.g., methanol, ethanol or methanol/THF).

Aldehyde 2 can be reductively aminated with a variety of amines, exemplified by, but not limited to, those illustrated in Table 1. The resulting esters can be converted to target hydroxamates by the methods listed. Amine Reducing Conditions Hydroxamate Conditions R NaBH(OAc)₃ HOAc, DCE 2 M HONH₂ in MeOH " " " " " " " " " " " " " " " " Ph(CH₂)₃NH₂ NaBH₃CN/MeOH/ HOAc Ph(CH₂)₃

An alternate synthesis of the compounds of this invention starts by reductive amination of 4-formyl cinnamic acid 3, illustrated below with 3-phenylpropylamine 13, using, for example, NaBH₃CN as the reducing agent in MeOH and HOAc as a catalyst. The basic nitrogen of the resulting amino acid 14 can be protected, for example, as t-butoxycarbamate (BOC) by reaction with di-t-butyldicarbonate to give 15.

The carboxylic acid can be coupled with a protected hydroxylamine (e.g., O-trityl hydroxylamine) using a dehydrating agent (e.g., 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (EDCI)) and a catalyst (e.g., 1-hydroxybenzotriazole hydrate (HOBT)) in a suitable solvent (e.g., DMF) to produce 16. Treatment of 16 with a strong acid (e.g., trifluoroacetic acid (TFA)) provides a hydroxamic acid 17 of the present invention. Additional examples of compounds that can be prepared by this method are:

Tertiary amine compounds can be prepared by a number of methods. Reductive amination of 30 with nicotinaldehyde 32 using NaBH₃CN as the reducing agent in dichloroethane and HOAc as a catalyst provides ester 34. Other reducing agents can be used (e.g., NaBH₄ and NaBH(OAc)₃) in other solvents or solvent mixtures in the presence or absence of acid catalysts (e.g., acetic acid, trifluoroacetic acid and the like). Reaction of ester 34 with HONH₂•HCl, NaOH in MeOH provides hydroxamate 36.

Tertiary amine compounds prepared by this methodology are exemplified, but not limited to, those listed in Table 2. Reducing Conditions Hydroxamate Conditions NaBH(OAc)₃ HOAc, DCE HONH₂•HCl/NaOMe/ MeOH NaBH(OAc)₃ HOAc, DCE HONH₂•HCl/NaOMe/ MeOH NaBH(OAc)₃ HOAc, DCE 2 M HONH₂ in MeOH NaBH₃CN/MeOH/ HOAc 2 M HONH₂ in MeOH NaBH(OAc)₃ HOAc, DCE 2 M HONH₂ in MeOH

An alternate method for preparing tertiary amines is by reacting a secondary amine with an alkylating agent in a suitable solvent in the presence of a base. For example, heating a dimethylsulfoxide (DMSO) solution of amine 11 and bromide 40 in the presence of (i-Pr)₂NEt yielded tertiary amine 42. Reaction of the tertiary amine 42 with HONH₂•HCl, NaOH in MeOH provides hydroxamate 43. The silyl group can be removed by any method known to those skilled in the art. For example, the hydroxamate 43 can be treated with an acid, e.g., trifluoroacetic acid, or fluoride to produce hydroxyethyl compound 44.

The hydroxamate compound, or salt thereof, is suitable for preparing pharmaceutical compositions, especially pharmaceutical compositions having deacetylase, especially histone deacetylase, inhibiting properties. Studies with athymic mice demonstrate that the hydroxamate compound causes HDA inhibition and increased histone acetylation in vivo, which triggers changes in gene expression that correlate with tumor growth inhibition.

The present invention further includes pharmaceutical compositions comprising a pharmaceutically effective amount of one or more of the above-described compounds as active ingredient. Pharmaceutical compositions according to the invention are suitable for enteral, such as oral or rectal, and parenteral administration to mammals, including man, for the treatment of tumors, alone or in combination with one or more pharmaceutically acceptable carriers.

The hydroxamate compound is useful in the manufacture of pharmaceutical compositions having an effective amount the compound in conjunction or admixture with excipients or carriers suitable for either enteral or parenteral application. Preferred are tablets and gelatin capsules comprising the active ingredient together with (a) diluents; (b) lubricants, (c) binders (tablets); if desired, (d) disintegrants; and/or (e) absorbents, colorants, flavors and sweeteners. Injectable compositions are preferably aqueous isotonic solutions or suspensions, and suppositories are advantageously prepared from fatty emulsions or suspensions. The compositions may be sterilized and/or contain adjuvants, such as preserving, stabilizing, wetting or emulsifying agents, solution promoters, salts for regulating the osmotic pressure and/or buffers. In addition, the compositions may also contain other therapeutically valuable substances. The compositions are prepared according to conventional mixing, granulating or coating methods, respectively, and contain preferably about 1 to 50% of the active ingredient.

Suitable formulations also include formulations for parenteral administration include aqueous and non-aqueous sterile injection solutions which may contain antioxidants, buffers, bacteriostats and solutes which render the formulation isotonic with the blood of the intended recipient; and aqueous and non-aqueous sterile suspensions which may include suspending agents and thickening agents. The formulations may be presented in unit-dose or multi-dose containers, for example, sealed ampules and vials, and may be stored in a freeze-dried (lyophilized) condition requiring only the addition of the sterile liquid carrier, for example, water for injections, immediately prior to use. Extemporaneous injection solutions and suspensions may be prepared from sterile powders, granules and tablets of the kind previously described.

As discussed above, the compounds of the present invention are useful for treating proliferative diseases. A proliferative disease is mainly a tumor disease (or cancer) (and/or any metastases). The inventive compounds are particularly useful for treating a tumor which is a breast cancer, genitourinary cancer, lung cancer, gastrointestinal cancer, epidermoid cancer, melanoma, ovarian cancer, pancreas cancer, neuroblastoma, head and/or neck cancer or bladder cancer, or in a broader sense renal, brain or gastric cancer; in particular (i) a breast tumor, an epidermoid tumor, such as an epidermoid head and/or neck tumor or a mouth tumor; a lung tumor, for example a small cell or non-small cell lung tumor, a gastrointestinal tumor, for example, a colorectal tumor; or a genitourinary tumor, for example, a prostate tumor (especially a hormone-refractory prostate tumor); or (ii) a proliferative disease that is refractory to the treatment with other chemotherapeutics; or (iii) a tumor that is refractory to treatment with other chemotherapeutics due to multidrug resistance.

In a broader sense of the invention, a proliferative disease may furthermore be a hyperproliferative condition such as leukemias, hyperplasias, fibrosis (especially pulmonary, but also other types of fibrosis, such as renal fibrosis), angiogenesis, psoriasis, atherosclerosis and smooth muscle proliferation in the blood vessels, such as stenosis or restenosis following angioplasty.

Where a tumor, a tumor disease, a carcinoma or a cancer are mentioned, also metastasis in the original organ or tissue and/or in any other location are implied alternatively or in addition, whatever the location of the tumor and/or metastasis.

The compound is selectively toxic or more toxic to rapidly proliferating cells than to normal cells, particularly in human cancer cells, e.g., cancerous tumors, the compound has significant antiproliferative effects and promotes differentiation, e.g., cell cycle arrest and apoptosis. In addition, the hydroxamate compound induces p21, cyclin-CDK interacting protein, which induces either apoptosis or G1 arrest in a variety of cell lines.

The following examples are intended to illustrate the invention and are not to be construed as being limitations thereto.

4-formylcinnamic acid methylester is produced by adding 4-formylcinnamic acid (25 g, 0.143 mol) in MeOH and HCl (6.7 g, 0.18 mol). The resulting suspension is heated to reflux for 3 hours, cooled and evaporated to dryness. The resulting yellow solid is dissolved in EtOAc, the solution washed with saturated NaHCO₃, dried (MgSO₄) and evaporated to give a pale yellow solid which is used without further purification (25.0 g, 92%). To a solution of tryptamine (16.3 g, 100 mmol) and 4-formylcinnamic acid methylester (19 g, 100 mmol) in dichloroethane, NaBH(OAc)₃ (21 g, 100 mmol) is added. After 4 hours the mixture is diluted with 10% K₂CO₃ solution, the organic phase separated and the aqueous solution extracted with CH₂Cl₂. The combined organic extracts are dried (Na₂SO₄), evaporated and the residue purified by flash chromatography to produce 3-(4-{[2-(1H-indol-3-yl)-ethylamino]-methyl}-phenyl)-(2E)-2-propenoic acid methyl ester (29 g). A solution of KOH (12.9 g 87%, 0.2 mol) in MeOH (100 mL) is added to a solution of HONH₂•HCl (13.9 g, 0.2 mol) in MeOH (200 mL) and a precipitate results. After 15 minutes the mixture is filtered, the filter cake washed with MeOH and the filtrate evaporated under vacuum to approximately 75 mL. The mixture is filtered and the volume adjusted to 100 mL with MeOH. The resulting solution 2M HONH₂ is stored under N₂ at -20° C for up to 2 weeks. Then 3-(4-{[2-(1H-indol-3-yl)-ethylamino]-methyl}-phenyl)-(2E)-2-propenoic acid methyl ester (2.20 g, 6.50 mmol) is added to 2 M HONH₂ in MeOH (30 mL, 60 mmol) followed by a solution of KOH (420 mg, 6.5 mmol) in MeOH (5 mL). After 2 hours dry ice is added to the reaction and the mixture is evaporated to dryness. The residue is dissolved in hot MeOH (20 mL), cooled and stored at -20°C overnight. The resulting suspension is filtered, the solids washed with ice cold MeOH and dried under vacuum, producing N-Hydroxy-3-[4-[[[2-(1H-indol-3-yl)-ethyl]-amino]methyl]phenyl]-2E-2-propenamide (m/z 336 [MH⁺]).

A solution of 3-(4-{[2-(1H-indol-3-yl)-ethylamino]-methyl}-phenyl)-(2E)-2-propenoic acid methyl ester (12.6 g, 37.7 mmol), (2-bromoethoxy)-tert-butyldimethylsilane (12.8 g, 53.6 mmol), (i-Pr)₂NEt, (7.42 g, 57.4 mmol) in DMSO (100 mL) is heated to 50° C. After 8 hours the mixture is partitioned with CH₂Cl₂/H₂O. The organic layer is dried (Na₂SO₄) and evaporated. The residue is chromatographed on silica gel to produce 3-[4-({[2-(tert-butyldimethylsilanyloxy)-ethyl]-[2-(1H+indol-3-yl)-ethyl]-amino}-methyl)-phenyl]-(2E)-2-propenoic acid methyl ester (13.1 g). Following the procedure described for the preparation of the hydroxamate compound in Example P1, 3-[4-({[2-(tert-butyldimethylsilanyloxy)-ethyl]-[2-(1H-indol-3-yl)-ethyl]-amino}-methyl)-phenyl]-(2E)-2-propenoic acid methyl ester (5.4 g, 11 mmol) is converted to N-hydroxy-3-[4-({[2-(tert-butyldimethylsilanyloxy)-ethyl]-[2-(1H-indol-3-yl)-ethyl]-amino}-methyl)-phenyl]-(2E)-2-propenamide (5.1 g,) and used without further purification. The hydroxamic acid (5.0 g, 13.3 mmol) is then dissolved in 95% TFA/H₂O (59 mL) and heated to 40 - 50°C for 4 hours. The mixture is evaporated and the residue purified by reverse phase HPLC to produce N-Hydroxy-3-[4-[[(2-hydroxyethyl)[2-(1H-indol-3-yl)-ethyl]-amino]methyl]phenyl]-2E-2-propenamide as the trifluoroacetate salt (m/z 380 [MH⁺]).

A suspension of LiAIH₄ (17 g, 445 mmol) in dry THF (1000 mL) is cooled to 0 °C and 2-methylindole-3-glyoxylamide (30 g, 148 mmol) is added in portions over 30 min. The mixture is stirred at room temperature for 30 min. and then maintained at reflux for 3 h. The reaction is cooled to 0 °C and treated with H₂O (17ml), 15% NaOH (aq., 17ml) and H₂O (51ml). The mixture is treated with MgSO₄, filtered and the filtrate evaporated to give 2-methyltryptamine which is dissolved in MeOH. Methyl 4-formylcinnamate (16.9 g, 88.8 mmol) is added to the solution, followed by NaBH₃CN (8.4 g) and AcOH (1 equiv.). After 1 h the reaction is diluted with NaHCO₃ (aq.) and extracted with EtOAc. The organic extracts are dried (MgSO₄), filtered and evaporated. The residue is purified by chromatography to give 3-(4-{[2-(2-methyl-1H-indol-3-yl)-ethylamino]-methyl}-phenyl)-(2E)-2-propenoic acid methyl ester. The ester is dissolved in MeOH, 1.0 M HCl/dioxane (1-1.5 equiv.) is added followed by Et₂O. The resulting precipitate is filtered and the solid washed with Et₂O and dried thoroughly to give 3-(4-{[2-(2-methyl-1H-indol-3-yl)-ethylamino]-methyl}-phenyl)-(2E)-2-propenoic acid methyl ester hydrochloride. 1.0 M NaOH (aq., 85 mL) is added to an ice cold solution of the methyl ester hydrochloride (14.9 g, 38.6 mmol) and HONH₂ (50% aq. solution, 24.0 mL, ca. 391.2 mmol). After 6 h, the ice cold solution is diluted with H₂O and NH₄Cl (aq., 0.86 M, 100 mL). The resulting precipitate is filtered, washed with H₂O and dried to afford N-hydroxy-3-[4-[[[2-(2-methyl-1H-indol-3-yl)-ethyl]-amino]methyl]phenyl]-2E-2-propenamide (m/z 350 [MH⁺]).

The following compounds are prepared by methods analogous to those disclosed in Examples P1, P2 and P3: Example STRUCTURE m/z (MH⁺) 1 426 2 3 4 325 5 6 7 8 465 9 10 11 12 420 13 420 14 15 465 16 385 17 550 18 432 19 366 20 350 21 22 442 23 338 24 464 25 541 26 27 28 417 29 30 31 380 32 436 33 34 493 35 477 36 586 37 513 38 378 39 408 40 449 41 438 42 452 43 507 44 565 45 46 47 48 49 50 51 470 52 53 548 54 623 55 456 56 478 57 394 58 422 59 479 60 603 61 477 62 539 63 523 64 65 66 67 68 539 69 495 70 71 379 72 478 73 462 74 378 75 76 493 77 503 78 350 79 549 80 471 81 350 82 418 83 486 84 524 85 424 86 364 87 440 88 420 89 390 90 91 92 484 93 498 94 490 95 96 475 97 525 98 422 99 528 100 448 101 437 102 451 103 505 104 519 105 514 106 507 107 626 108 499 109 110 111 429 112 464 113 432 114 422 115 390 116 501 117 484 118 119 587 120 602 121 539 122 123 528 124 487 125 126 556 127 128 129 552 130 519 131 450 132 464 133 558 134 533 135 136 527 137 381 138 364 139 140 448 141 558 142 143 427 144 145 432 146 384 147 354 148 149 150 151 152 153 154 350 155 366 156 408 157 322 158 364 159 364 160 378 161 350 162 463 163 164 381 165 463 166 476 167 168 169 170 368 171 493 172 527 173 515 174 323 175 540 176 441 177 276 178 179 455 180 181 336 182 347 183 447 184 185 420 186 424 187 422 188 189 398 190 418 191 350 192 193 352 194 499 195 408 196 394 197 499 198 199 200 350 201 202 203 204 365 205 465 206 207 410 208 410 209 210 366 211 352 212 213 368 214 338 215 356 216 408 217 368 218 396 219 220 342 221 392 222 412 223 337 224 337 225 456 226 364 227 481 228 355 229 312 230 424 231 232 351 233 392 234 235 236 322 237 238 366 239 240 368 241 242 406 243 398 244 442 245 350 246 364 247 402 248 418 249 364 250 251 408 252 253 254 413 255 405 256 257 394 258 390 259 434 260 386 261 368 262 412 263 406 264 265 378

The compounds of Examples 1-265 show an HDA enzyme IC₅₀ in the range from about 0.005 to about 0.5 µM.

Cell lines H1299 (human lung carcinoma cell) and HCT116 (colon tumor cell) are obtained from the American Type Culture Collection, Rockville, MD. The cell lines are free of Mycoplasma contamination (Rapid Detection System by Gen-Probe, Inc., San Diego, CA) and viral contamination (MAP testing by MA BioServices, Inc., Rockville, MD). The cell lines are propagated and expanded in RPMI 1640 medium containing 10% heat-inactivated FBS (Life Technologies, Grand Island, NY). Cell expansions for implantation are performed in cell factories (NUNC, purchased from Fisher Scientific, Springfield, NJ). Cells are harvested at 50-90% confluency, washed once with HBSS (Hank's Balanced Salt Solution) containing 10% FBS, and suspended in 100% HBSS.

Cell proliferation is measured with a commercial MTS kit (Promega, Madision, Wis.) assay using an adaptation of published procedures, for example, that disclosed in Feasibility of drug screening with panels of human tumor cell lines using a microculture tetrazolium assay, Alley MC, et al., Cancer Res. 1988; 48:589-601. Cells are plated in 96-well tissue culture dishes, with top and bottom rows left empty. H1299 and HCT116 cells are suspended in complete media at a density of 5.3 x 10³ and 3.6 x 10³ cell/mL, respectively, and 190 µl are added per well. Each cell line is added to one half of the plate. Complete medium (200 µL) is added to the top and bottom rows. Twenty-four hours later, 10 µl of MTS solution is added to one of the plates to determine the activity at the time of compound addition (T₀). The plate is incubated at 37 °C for 4 hours and the OD₄₉₀ is measured on a Molecular Devices Thermomax at 490 nm using the Softmax program. The T₀ plate serves as a reference for initial activity at the beginning of the experiment.

Five serial dilutions (1:4) of each compound are made in a 96-deep well plate with the highest concentrations on the edge of plate. Two cell lines are tested with two compounds per plate. Ten microliters of each of the five dilutions are added in triplicate and complete medium alone is added to columns six and seven. The plates are incubated at 37 °C for 72 hours. The MTS solution is added (as for the To plate) and read four hours later.

In order to analyze the data, the average background value (media alone) is subtracted from each experimental well; the triplicate values are averaged for each compound dilution. The following formulas are used to calculate percent growth.
If X > T₀, % Growth = ((X-T₀)/(GC -T₀)) x 100
If X < T₀, % Growth = (X-T₀)/T₀) x 100
in which T₀ = (average value of cell viability at time 0) - background
GC = average value of untreated cells (in triplicate) - background
X = average value of compound treated cells (in triplicate) - background
The"% Growth" is plotted against compound concentration and used to calculate IC₅₀s employing the linear regression techniques between data points to predict the concentration of compounds at 50% inhibition.

Lactate salts of N-hydroxy-3-[4-[[[2-(1H-indol-3-yl)-ethyl]-amino]methyl]phenyl]-2E-2-propenamide (CMD1), N-hydroxy-3-[4-[[(2-hydroxyethyl)[2-(1H-indol-3-yl)-ethyl]-amino]methyl]phenyl]-2E-2-propenamide (CMD2), N-hydroxy-3-[4-[[[2-(5-methoxy-1H-indol-3-yl)-ethyl]-amino]methyl]phenyl]-2E-2-propenamide (CMD3), N-hydroxy-3-[4-[[[2-(5-fluoro-1H-indol-3-yl)-ethyl]-amino]methyl]phenyl]-2E-2-propenamide (CMD4), N-hydroxy-3-[4-[[[2-(benzofur-3-yl)-ethyl]-amino]methyl]phenyl]-2E-2-propenamide (CMD5) having a purity of higher than 95% are dissolved in pure dimethylsulfoxide (DMSO) to create a stock solution. The stock solution is diluted with 5% dextrose injection, USP, just prior to dosing. In addition, N-(2-aminophenyl)-4-[N-pyridin-3-yl)methoxycarbonylaminomethyl]benzamide is synthesized in accordance with Example 48 of EP 0 847 992 and used as a control compound (CMDC). Inhibition of cell growth in monolayer for 72 hours of compound treatment is measured in triplicate experiments and used to derive the IC₅₀ by MTS assay. The results are shown in Table B1. Monolayer Growth IC₅₀ (µM) Compound H1299 HCT116 CMD1 0.40 0.03 CMD2 0.15 0.01 CMD3 0.58 0.03 CMD4 0.28 0.03 CMD5 0.18 0.03 CMDC 6.8 0.67 The results show that the hydroxamate compounds of the present invention are highly active in inhibition of tumor cell growth. In addition to the above results, it has been observed that the compounds selectively inhibited tumor cells while showing minimal inhibition activities in non-tumorous cells.

The cells treated with the hydroxamate compounds are also tested for the induction of p21 promoter, which is a key mediator of G1 arrest and differentiation. The hydroxamate compounds activate the p21 promoter to a readily detectable level at a concentration within two-fold of their respective IC₅₀ for monolayer cell growth inhibition in H1299. Without being bound by any particular theory, the correlation appears to demonstrate that HDA inhibition leads to transcriptional activation of genes that inhibit tumor cell proliferation.

HDA is partially purified from H1299, human non-small cell lung carcinoma cells (obtained from American Type Culture Collection, 12301 Parklawn Drive, Rockville, MD 20852, USA). Cells are grown to 70-80% confluence in RPMI media in the presence of 10% FCS, harvested and lysed by sonication. The lysate is centrifuged at 23, 420g for 10-15 min, the supernatant is applied to a Hiload 26/10 High performance Q-sepharose column (Amersham Pharmacia Biotech), and equilibrated with a buffer containing 20 mM Tris pH8.0, 1 mM EDTA, 10 mM NH₄Cl₂, 1 mM β-Mercaptoethanol, 5% glycerol, 2 µg/mL aprotinin, 1 µg/mL leupeptin, and 400 mM PMSF. Proteins are eluted in 4mL aliquotes with a linear gradient from 0-500 mM NaCl in the above buffer at a flow rate of 2.5 mL/min. Each preparation of partially purified HDA enzyme is titrated to determine the optimal amount needed to obtain a signal to noise ratio of at least 5 to 1. Generally, 20-30 µl of partially purified HDA (5-10 mg protein/mL) is mixed with 2 µL of compound solution in DMSO in a deep well titer plate (Beckman). The compounds are serially diluted in DMSO to generate stocks at 20-fold of the assay concentrations. Final concentrations of compounds in the assay are 10 µM, 2 µM, 400 nM, 80 nM, and 16 nM with the final percentage of DMSO in each enzyme reaction equaling 0.1%. Each concentration of compound is assayed in duplicate. The substrate used in the reaction is a peptide of amino acid sequence, SGRGKGGKGLGKGGAKRHRKVLRD, corresponding to the twenty-four N-terminal amino acids of human histone H4, biotinylated at the N-terminus and penta-acetylated, at each lysine residue with ³H-acetate. To initiate the reaction, the substrate is diluted in 10 µL of Buffer A (100 mM Tris pH 8.0, 2 mM EDTA), added to the enzyme mixture and collected at the bottom of the deep well plate by centrifugation for 5 minutes at 1500 rpm. Following centrifugation, the mixture is incubated at 37 °C for 1.5 hr. The reaction is stopped by the addition of 20 µL of the Stop Buffer (0.5N HCl, 0.08M Acetic Acid). At this point, the assay proceeds to the robotic extraction phase or is frozen for several days at -80 °C.

The extraction of enzymatically cleaved ³H-acetate groups from the reaction mixture is achieved with the solvent TBME (t-butyl methyl ether) using the Tomtec Quadra 96 workstation. A program is written to add 200 µL of TBME to a 96 "deep well" plate. The workstation is programmed to aspirate 50 µL of air followed by 200 µL of TBME and finally another 25 µL of air, which is dispensed into the each well of the plate. The contents of the deep well were mixed thoroughly by pipetting 160 µL up and down 10 times. Before addition of TBME to the reaction mixture, it is necessary to "pre-wet" the pipette tips with TBME to prevent the solvent from dripping during the transfer to the deep well plate. The organic and aqueous phases in the deep well are separated by centrifugation at 1500 rpm for 5 min. Opti-Phase Supermix liquid scintillation cocktail (200 µL) (Wallac) is added to each well of the 96-well Trilux plate (Wallac). The deep well and Trilux plates are placed back on the workstation programmed to aspirate 25 µL of air into the pipette tips followed by 100 µL of the upper TBME phase and transfer it into the Trilux plate. The solutions are mixed by pipetting and expelling 50 µL, five times, within the same well. The Trilux plate is covered with clear film and read on a 1450 MicroBeta Trilux liquid scintillation and luminescence counter (Wallac) with a color/chemical quench and dpm correction.

In order to determine the IC₅₀ values, the data are analyzed on a spreadsheet. The analysis requires a correction for the background luminescence that is accomplished by subtracting the dpm values of wells without ³H substrate from the experimental wells. The corrected dpm values along with the concentrations of the compounds are used to calculate IC₅₀ using the user-defined spline function. This function utilizes linear regression techniques between data points to calculate the concentration of compounds that produced 50% inhibition. The results are shown in Table B2. Compound HDA Enzyme Activity IC₅₀ (µM) CMD1 0.032 CMD2 0.063 CMD3 0.014 CMD4 0.014 CMD5 0.016 CMDC > 10

The A549 non-small cell lung human tumor cell line is purchased from the American Type Culture Collection, Rockville, MD. The cell line is free of Mycoplasma contamination (Rapid Detection System by Gen-Probe, Inc., San Diego, CA) and viral contamination (MAP testing by MA BioServices, Inc., Rockville, MD). The cell line is propagated and expanded in RPMI 1640 medium containing 10% heat-inactivated FBS (Life Technologies, Grand Island, NY). Cell expansions for implantation are performed in cell factories (NUNC, purchased from Fisher Scientific, Springfield, NJ). Cells are harvested at 50-90% confluency, washed once with HBSS containing 10% FBS, and suspended in 100% HBSS.

Outbred athymic (nu/nu) female mice ("Hsd:Athymic Nude-nu" from Harlan Sprague Dawley, Indianapolis, IN) are anesthetized with Metofane (Mallinckrodt Veterinary, Inc., Mundelein, IL), and 100 µL of the cell suspension containing 1x10⁷ cells is injected subcutaneously into the right axillary (lateral) region of each animal. Tumors are allowed to grow for about 20 days until a volume of -100 mm³ is achieved. At this point, mice bearing tumors with acceptable morphology and size are sorted into groups of eight for the study. The sorting process produces groups balanced with respect to mean and range of tumor size. Antitumor activity is expressed as % T/C, comparing differences in tumor volumes for treatment group (T) to vehicle control group (C). Regressions are calculated using the formula: (1-T/T₀) x 100%, where T is the tumor volume for the treatment group at the end of the experiment, and T₀ is the tumor volume at the beginning of the experiment.

CMD1 is administered intravenously, once daily 5x/week for three weeks, at doses of 10, 25, 50, or 100 mg/kg. The final DMSO concentration is 10%. Each test group has eight mice. Tumors are measured, and individual animal body weights recorded. Table B3 shows the results on the 41^st day. COMPOUND DOSE (mg/kg) Δ MEAN TUMOR VOLUME*¹ (mm³ ± SEM*³) % T/C Δ % BODY WEIGHT*² (% ± SEM*³) 10% DMSO/D5W*⁴ - 376 ± 55 - +11.9 ± 0.2 CMD1 10 121 ± 27 32 + 1.3 ± 0.3 CMD1 25 77 ± 32 20 - 0.9 ± 0.3 CMD1 50 57 ± 10 15 - 0.4 ± 0.3 CMD1 100 28 ± 25 7 + 0.4 ± 0.3 Note: *1. Difference in mean tumor volume for a group of animals at the end of the experiment minus mean tumor volume at the beginning.
*2. Difference in body weight for a group of animals at the end of the experiment minus mean tumor volume at the beginning.
*3. Standard error of the mean.
*4. 5% dextrose injection, USP.

Example B3 repeated except CMD2 is used. Table B4 shows the results. COMPOUND DOSE (mg/kg) Δ MEAN TUMOR VOLUME mm³ ± SEM) % T/C Δ % BODY WEIGHT (% ± SEM) 10% DMSO/D5W - 135 ± 43 - + 6.7 ± 1.1 CMD2 25 37 ± 16 27 - 4.2 ± 2.5 CMD2 50 29 ± 15 21 - 2.9 ± 1.5

Example B3 is repeated except the HCT116 colon tumor cell line is used in place of the A549 cell line. The HCT116 cell line is also obtained from American Type Culture Collection, Rockville, MD, and the cell line is free of Mycoplasma contamination and viral contamination. The results are recorded on the 34^th day and are shown in Table B5. COMPOUND DOSE (mg/kg) Δ MEAN TUMOR VOLUME (mm³ ± SEM) % T/C Δ % BODY WEIGHT (% ± SEM) 10% DMSO/D5W - 759 ± 108 - - 0.4 ± 0.4 CMD1 50*¹⁰ 186 ± 40 25 - 7.4 ± 0.8 CMD1 100 140 ± 38 18 - 3.2 ± 0.4 Note: *10. Seven mice are tested in this group.

Example B4 is repeated except the HCT116 colon tumor cell line is used in place of the A549 cell line. The HCT116 is also obtained from American Type Culture Collection, Rockville, MD, and the cell line is free of Mycoplasma contamination and viral contamination. The results are recorded on the 34^th day and are shown in Table B6. COMPOUND DOSE (mg/kg) Δ MEAN TUMOR VOLUME (mm³ ± SEM) % T/C Δ% BODY WEIGHT (% ± SEM) 10% DMSO/D5W - 759 ± 108 - - 0.4 ± 0.4 CMD2 10 422 ± 75 56 -10.2 ± 0.5 CMD2 25 305 ± 47 40 - 7.0 ± 0.2 CMD2 50 97 ± 30 13 - 7.3 ± 0.3 CMD2 100 132 ± 30 17 - 9.4 ± 0.4

Annexin V binding was used as a marker for the early stages of apoptosis. A549, HCT116 and Normal Dermal Human Fibroblasts (NDHF) cells are treated separately with four compounds (CMD1, CMD2, CMD3 and CMD4) for 24 or 48 hours, stained with annexin V and compared to cells treated similarly with vehicle (DMSO). Cells are examined by fluorescence microscopy. Those undergoing apoptosis exhibit green fluorescent membrane staining. Viability is assessed by the counterstain, propidium iodide. Cells detected by red fluorescence are not viable. A small percentage of A549 and the majority of HCT116 cells exhibit cell surface staining with annexin V after 24 hour exposure to each of the four compounds. After 48 hour treatment, the majority of the A549 and HCT116 stain with annexin V and/or propidium iodide indicating that the compounds induce apoptotic cell death. In contrast, NDHF cells do not show noticeable annexin V staining after 24 hour exposure and limited annexin V staining with CMD3 after 48 hour. These data show that NDHF cells predominantly underwent non-lethal growth arrest upon compound treatment, consistent with the cell cycle profile.

The staining results demonstrate that the hydroxamate compounds of the present invention cause tumor cells to die by apoptosis, while causing normal fibroblast to predominantly undergo cell cycle arrest, clearly demonstrating the selective efficacy of the present compounds.